Catalyst for the hydrotreatment of a heavy hydrocarbon feedstock

ABSTRACT

Disclosed is a method of hydrotreating a heavy hydrocarbon feedstock using a hydrotreating catalyst having specific properties that make it effective in converting nitrogen, sulfur and micro-carbon residue of a heavy hydrocarbon feedstock. The catalyst comprises a calcined support particle impregnated with a Group 6 metal component (e.g., molybdenum), a nickel component, and a phosphorus component present at concentrations in the catalyst such that the atomic ratio of the Group 6 metal-to nickel metal are within a specified range. The nickel metal acid extractability property of the catalyst is at least 50 percent.

This non-provisional application claims the benefit of U.S. PatentApplication No. 61/892,024 filed Oct. 17, 2013, which is incorporatedherein by reference.

FIELD OF THE INVENTION

This invention relates to a catalyst composition, a method of making thecatalyst composition and use thereof in the hydrotreatment of heavyhydrocarbon feedstocks.

BACKGROUND OF THE INVENTION

The catalytic hydrotreatment of hydrocarbon feedstock to removeimpurities such as sulfur, nitrogen, and metal compounds is a commonlyused process to improve or upgrade such hydrocarbon feedstock. Thistreatment to remove sulfur and nitrogen from heavy hydrocarbon feedstockis necessary due to various environmental regulations implemented by theUnited States and other countries. For example, the maximum sulfurconcentration in on-road diesel is 15 parts per million (ppm) in theUnited States. Other organizations are pushing for limits as low as 5 to10 ppm sulfur in diesel.

In a typical hydrotreating process, the hydrocarbon feedstock iscontacted with a hydrotreating catalyst in the presence of hydrogenunder process conditions that provide for a treated hydrocarbon product.The hydrotreating catalysts used in these processes generally arecomposed of an active phase that can include a component from the Group6 metals, e.g. molybdenum (Mo) or tungsten (W), and a component fromeither the Group 9 metals, e.g. cobalt (Co), or the Group 10 metals,e.g. nickel (Ni), or a combination thereof, supported on a porous,refractory inorganic oxide material. The references herein to theelements by grouping within the periodic table are as they are listedand defined by the International Union of Pure and Applied Chemistry(IUPAC) Periodic Table of the Elements.

The hydrotreatment of heavy hydrocarbon feedstock is particularlydifficult; because, such feeds tend to have high concentrations ofcontaminating sulfur and nitrogen compounds and may require the use ofmore severe process conditions than those needed to treat lighterhydrocarbon feedstock. As the quality of feedstock declines, thereaction conditions required to achieve a desired level ofhydrotreatment tend to become more severe (e.g., increased temperaturesor pressures). This increases production costs and causes more rapiddepletion of catalyst activity.

There is a continuing need for improving catalyst performance to offsetthe decreasing quality of feedstock and the increased processing costsassociated therewith. In particular, the ability of a catalyst toachieve acceptable sulfur and nitrogen removal at lower temperatures isquite valuable; because, lower temperatures require less energy inputwhich directly reduces production costs.

One catalyst found to be useful in the hydroprocessing of heavyhydrocarbon feedstocks is disclosed in U.S. Pat. No. 4,738,944 (Robinsonet al.). The catalyst disclosed in this patent contains nickel,phosphorus and molybdenum supported on alumina, and it contains up toabout 10, usually from 1 to 8 percent, and preferably from 2 to 6percent by weight of nickel metal components, calculated as themonoxide. The catalyst also contains from about 16 to about 23 andpreferably from 19 to 21.5 percent by weight molybdenum metalcomponents, calculated as molybdenum trioxide (MoO₃). The pore structureof the catalyst is such that it has a narrow pore size distribution withat least about 75 percent, preferably at least about 80 percent, andmost preferably at least about 85 percent of the total pore volume inpores of diameter from about 50 to about 110 angstroms. Ordinarily, thecatalyst has less than about 10 percent of its total pore volume inpores of diameter below about 50 angstroms.

Another hydroprocessing catalyst is disclosed in U.S. Pat. No. 7,824,541(Bhan) that is particularly useful in the treatment of distillatefeedstocks to manufacture low-sulfur distillate products. This catalystis a co-mulled mixture of molybdenum trioxide, a Group VIII metalcompound, and an inorganic oxide material. The co-mulled mixture iscalcined. The molybdenum content of the catalyst is in the range of from10.5 to 33 wt. %, calculated as an oxide. If the Group VIII metalcomponent is nickel, it is present in the catalyst in the range of from3.8 to 15.3 wt. %, calculated as an oxide. The catalyst also has a meanpore diameter that is in a specific and narrow range of from 50 to 100angstroms. There is less than 4.5 percent of the total pore volume thatis contained in its macropores having pore diameters greater than 350angstroms and less than 1 percent of the total pore volume contained inits macropores having pore diameters greater than 1000 angstroms.

Disclosed in U.S. Pat. No. 7,871,513 (Bhan) is a catalyst that is usefulin the hydroprocessing of heavy hydrocarbon feedstocks. This catalyst isa calcined mixture made by calcination of a formed particle of a mixturecomprising molybdenum trioxide, a nickel compound, and an inorganicoxide material. The molybdenum content of the catalyst is in the rangeupwardly to 18 wt. %, calculated as an oxide. The nickel content of thecatalyst is in the range upwardly to 5.1 wt. %, calculated as an oxide.The molybdenum source used in the preparation of the catalyst is in theform of molybdenum trioxide that is in a finely divided state.

While the catalysts described above have been shown to have goodhydroprocessing activity, there are continuing efforts to find new orimproved catalyst compositions having increased catalytic activity orimproved stability, or both. Any improvement in catalyst activity canresult in the lowering of required reactor temperatures to obtain aproduct with reduced concentrations of nitrogen or sulfur as compared toa feedstock that is contaminated with these components. The lowerreactor temperatures provide for energy savings and will extend the lifeof a catalyst. There also are ongoing efforts to find more economicalmethods of manufacturing the catalyst compositions.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a method of making a catalystcomposition useful in the hydrotreatment of a heavy hydrocarbonfeedstock. The method comprises the steps of providing a calcinedsupport particle, comprising an inorganic oxide material; impregnatingthe calcined support particle with an aqueous impregnation solution,wherein the aqueous impregnation solution comprises a Group 6 metalcompound, a nickel compound and a phosphorus compound, and wherein theaqueous impregnation solution has an atomic ratio of nickelmetal-to-Group 6 metal that is in the range of from 0.5 and 0.75, tothereby provide an impregnated support particle; and conducting acontrolled low-temperature calcination of the impregnated supportparticle so as to thereby provide a calcined catalyst particle having anickel metal acid extractability property of at least 50%.

In another aspect, the invention encompasses a catalyst composition,comprising a calcined particle, wherein the calcined particle comprisesan impregnated calcined support particle, having been subjected to acontrolled low-temperature calcination to provide the calcined particle,wherein the calcined particle comprises a Group 6 metal component and anickel component in proportions such that the atomic ratio of the nickelmetal to the Group 6 metal is in the range of from 0.5 and 0.75, andwherein the calcined particle has a nickel metal acid extractabilityproperty of at least 50%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph illustrating the sulfur conversion achieved by use inhydrotreating a heavy feedstock of a composition that is representativeof an inventive catalyst produced according to the invention incomparison to the sulfur conversion achieved with a reference catalyst.

FIG. 2 is a graph illustrating the weight average bed temperature (WABT)achieved by use in hydrotreating a heavy feedstock of a compositionrepresentative of an inventive catalyst produced according to theinvention relative to the WABT achieved with a reference catalyst.

FIG. 3 is a graph illustrating nitrogen conversion achieved by use inhydrotreating a heavy feedstock of a composition representative of aninventive catalyst produced according to the invention in comparison tothe nitrogen conversion achieved with a reference catalyst.

FIG. 4 is a graph illustrating MCR conversion achieved by use inhydrotreating a heavy feedstock of a composition representative of aninventive catalyst produced according to the invention in comparison tothe MCR conversion achieved with a reference catalyst.

DETAILED DESCRIPTION OF THE INVENTION

A novel catalyst composition has been discovered that is especiallyuseful in the hydrotreatment of heavy hydrocarbon feedstocks that havesignificant concentrations of sulfur, nitrogen, metals such as vanadiumand nickel, and micro-carbon residue (MCR). This catalyst compositionexhibits exceptional nitrogen, sulfur, and MCR conversion activity atlower operating temperatures than comparative catalysts.

The inventive catalyst composition comprises a calcined particle thatcomprises a calcined support particle that has been impregnated withcatalytic metals and thereafter subjected to a low-temperaturecalcination. The calcined support particle used in the preparation ofthe calcined particle, or catalyst composition, comprises an inorganicoxide support material (e.g., alumina) that has been agglomerated andcalcined under a high-temperature calcination condition to therebyprovide the calcined support particle. This calcined support particle isimpregnated with a Group 6 metal (e.g., molybdenum) component, a nickelcomponent and a phosphorus component in such relative proportions thatthe atomic ratio of the nickel metal-to-Group 6 metal in the resultingimpregnated calcined support particle is within a specific range ashereafter defined. The impregnated calcined support particle issubjected to a controlled low-temperature calcination to provide thefinal calcined particle, or catalyst composition, having a nickel metalacid extractability property, as defined hereinafter, of at least 50%.

In the preparation of the inventive catalyst composition, the calcinedsupport particle is impregnated with an impregnation solution whichcomprises either active metal compounds or active metal precursors thatare present in the impregnation solution in specifically definedproportions. One of the essential features of the invention is for theimpregnation solution to have certain compositional and other propertiesthat cooperate with other features of the invention to give the finalcalcined catalyst particle of the catalyst composition having enhancedcatalytic properties. Among these features, it is important for thecalcined support particle used in the preparation of the inventivecatalyst to be prepared in a specific way such that its properties willwork together with the other aspects of the composition and preparationmethod to provide the final catalyst composition of the invention havingimproved properties as described herein.

The calcined support particle used in the preparation of the inventivecatalyst comprises an inorganic oxide material selected from a group ofinorganic oxides that typically are used to carry catalytically activemetal components. Suitable inorganic oxides can include porous inorganicrefractory oxides, such as, for example, silica, alumina, andsilica-alumina, that provide the surface structure properties requiredfor the inventive catalyst. Particulate or powder alumina orsilica-alumina is preferred with particulate or powder alumina beingmost preferred.

To prepare the calcined support particle, the inorganic oxide materialis shaped or formed or agglomerated into a particle that is calcinedunder a specifically defined high-temperature calcination condition thatprovides the inventive catalyst composition having its special andenhanced catalytic properties when the high-temperature calcination isdone in combination with the low-temperature calcination of theimpregnated calcined support particle and with the impregnation of thecalcined support particle with an impregnation solution havingparticularly defined properties.

The support particle may be formed or shaped or agglomerated by anysuitable method known to those skilled in the art provided that thesupport particle can subsequently be heat treated or calcined inaccordance with the invention to provide a calcined support particlehaving the necessary properties of the invention. Examples of knownshaping methods include rolling, tableting, pelletizing, and extruding.

It is preferred to use an extrusion method to form the shaped supportparticle that is calcined to provide the calcined support particle usedin preparing the inventive catalyst composition. To make the shapedsupport particle by this method, the starting inorganic oxide materialis mixed with water and a suitable acid compound, in proportions and ina manner so as to form an extrudable paste suitable for extrudingthrough an extrusion die to thereby form an extrudate.

In certain embodiments of the invention, the support particle is made bymixing a nickel compound with the starting inorganic oxide material soas to provide a small concentration of nickel in the calcined supportparticle. This nickel concentration can be in the range of upwardly toabout 3 weight percent of the calcined support particle, based on thenickel as an oxide, regardless of its actual form in the calcinedsupport particle. The nickel compound may, for example, be selected fromsuch compounds as nickel oxide, nickel nitrate, nickel carbonate, nickelacetate, nickel chloride, and nickel sulfate, with the preferred nickelcompound being either nickel oxide or nickel nitrate.

If nickel is to be incorporated into the support particle of theinvention, a desirable concentration of the nickel therein is in therange of from 0.1 wt. % to 2 wt. % of the calcined support particle,based on the nickel as an oxide. A more desirable concentration ofnickel in the calcined support particle is in the range of from 0.5 wt.% to 1.5 wt. %.

The formed extrudate used as the shaped support particle used inproviding the calcined support particle of the invention may have anycross-sectional shape such as cylindrical shapes, polylobal shapes orany other suitable shape. A typical size of extrudate has across-sectional diameter in the range of from about 1/10 inch (2.54 mm)to 1/32 inch (0.79 mm) and a length-to-diameter ratio in the range offrom 2:1 to 5:1. The preferred shape is a tri-lobe.

The shaped support particle is then dried under standard dryingconditions that can include a drying temperature in the range of from50° C. to 200° C., preferably, from 75° C. to 175° C., and, mostpreferably, from 90° C. to 150° C.

It is a significant, if not a critical, feature of the invention thatthe shaped support particle, after its drying, is calcined under ahigh-temperature calcination condition. What is meant herein by ahigh-temperature calcination condition is that the temperature at whichthe shaped support particle is calcined is elevated in relationship tothe temperature at which the impregnated support particle is calcined.

It is believed that one aspect of the invention that is responsible forthe enhanced properties of the inventive catalyst composition is thatthe calcination of the support particle is conducted at a significantlyhigher calcination temperature than the calcination temperature at whichthe impregnated support particle is calcined. This is thought to bebecause the different calcination temperatures have different affectsupon the resulting physical properties, such as pore structure, of thematerials being calcined.

The high-temperature calcination of the shaped support particle isconducted in the presence of an oxygen-containing fluid, such as air, ata temperature that is preferably elevated above the temperature at whichthe impregnated support particle undergoes its calcination. In general,the temperature at which the shaped support particle is calcined toprovide the calcined support particle is in the range of from 450° C.(842° F.) to 760° C. (1400° F.). The preferred calcination temperatureis in the range of from 510° C. (950° F.) to 730° C. (1346° F.), and,more preferred, it is from 540° C. (1004° F.) to 705° C. (1301° F.).

The time period under which the shaped support particle is calcined issuch as is necessary to provide the calcined support particle having thenecessary properties required for the invention, but, typically, it isin the range of from about 0.25 hours to 10 hours. More typically,period time for which the shaped support particle is calcined is from0.5 to 6 hours.

The mean pore diameter of the calcined support particle is typically inthe range of from 50 Å to150 Å. More typically, the mean pore diameteris in the range of form 80 Å to 120 Å, or in the range of from 90 Å to110 Å.

The calcined support particle can have a surface area (determined by theBET method employing N₂, ASTM test method D 3037) that is in the rangeof from 150 m²/g to 350 m²/g, preferably, from 200 m²/g to 320 m²/g,and, most preferably, from 220 m²/g to 300 m²/g.

The Hg pore volume of the calcined support particle can be in the rangeof from 0.4 cc/g to 1.1 cc/g, preferably, from 0.5 cc/g to 1.0 cc/g,and, most preferably, from 0.6 cc/g to 0.9 cc/g.

Another important feature of the invention requires the metalsimpregnation solution that is used to incorporate the catalytic metalsinto the calcined support particle to be an aqueous impregnationsolution. The aqueous impregnation solution comprises a Group 6 metal(e.g., molybdenum) component, a nickel component, and a phosphorouscomponent that are present at concentrations such that the atomic ratioof nickel metal-to-Group 6 metal are within a specifically defined andnarrow range, as hereafter defined.

It is believed that the atomic ratio of nickel metal-to-Group 6 metalatomic of the aqueous impregnation solution affects its properties andthe way the nickel atoms move onto the surfaces of the molybdenum atomsor molybdenum stacks that are formed in the final calcined catalystparticle. It is undesirable for the nickel atoms to move toward or beincorporated onto the alumina surfaces instead of residing upon theother metals that are incorporated onto the calcined support particle.

It is thought also that there is a relationship between the pH of theaqueous impregnation solution and its nickel metal-to-Group 6 metalatomic ratio, and that the pH of the aqueous impregnation solutionfurther impacts in some way the distribution of these metal componentswithin the calcined support particle when it is impregnated with theaqueous impregnation solution.

Taking these factors into consideration, it has been found that it isadvantageous for the atomic ratio of nickel metal-to-Group 6 metal inthe aqueous impregnation solution of the invention to be in the range offrom 0.4 to 0.8 and, in an embodiment, for the pH of the aqueousimpregnation solution to be in the range up to about 4. It is preferredfor the atomic ratio of nickel metal-to-Group 6 metal to be range in therange of from 0.45 to 0.75, and, more preferred, from 0.5 to 0.7.

The pH of the aqueous impregnation solution should be in the range offrom 0.1 to 4, and, preferably, the pH is in the range of from 0.5 to3.5. It is more preferred for the pH to be in the range of from 0.75 to3.

To prepare the aqueous impregnation solution, the Group 6 metalcomponent, nickel component, and phosphorous component are mixedtogether with water and dissolved. Slight heating of the mixture may beapplied as required to help in dissolving the components, and a suitableacid may be used to assist in the dissolution of the components and toprovide for an aqueous impregnation solution having the necessary pH asdescribed above. Typically, a suitable acid can include a mineral acidsuch as nitric acid.

Among the Group 6 metals of chromium, molybdenum, and tungsten thatmight suitably be used in the preparation of the aqueous impregnationsolution, molybdenum is preferred. Molybdenum compounds that maysuitably be used in the preparation of the aqueous impregnation solutioninclude, but are limited to, molybdenum trioxide and ammonium molybdate.Molybdenum trioxide is the preferred molybdenum compound used in thepreparation of the aqueous impregnation solution.

The molybdenum concentration in the impregnation solution that isincorporated into the calcined support particle to provide theimpregnated calcined particle should be such as to provide for the finalcalcined particle having a molybdenum content in the range upwardly to18 weight percent (wt. % calculated as MoO₃), with the weight percentbeing based on the total weight of the calcined particle. Also, themolybdenum content of the calcined particle should be equal to orgreater than 9 wt. %, calculated as MoO₃. However, it is desirable forthe amount of molybdenum that is contained in the impregnation solutionto be such as to provide a calcined particle having a molybdenum contentin the range of from 9 to 18 wt. %, but, preferably, from 12 to 17.5 wt.%, and, most preferably, from 12.8 to 17.0 wt. % (calculated as MoO₃).

Nickel compounds suitable for use in the preparation of the aqueousimpregnation solution include, but are not limited to, nickelhydroxides, nickel nitrates, nickel acetates, and nickel oxides. Nickeloxide and nickel nitrate are the preferred nickel compounds with nickeloxide being the most preferred.

The amount of nickel contained in the aqueous impregnation solutionshould be such as to provide for a calcined particle having a nickelcontent in the range upwardly to 7 weight percent (wt % calculated asNiO), with the weight percent being based on the total weight of thecalcined particle. Also, the nickel content of the calcined particleshould be equal to or greater than 2 wt. %, calculated as NiO. However,it is desirable for the amount of the nickel compound that is containedin the aqueous impregnation solution to be such as to provide for thecalcined particle having nickel content in the range of from 2 to 7 wt.%, but, preferably, from 2.5 to 4.8 wt. % and, most preferably, from 3to 4.3 wt. % (calculated as NiO).

The phosphorus compound used in the preparation of the aqueousimpregnation solution typically is in the form of a phosphorouscontaining solution that is prepared using a salt compound of phosphorusor an oxyacid of phosphorus. Suitable salt compounds include, but arenot limited, to phosphate compounds with a cation such as sodium,potassium, rubidium, cesium, or ammonium, or any of the aqueous forms ofphosphate (e.g. phosphate ion (PO₄ ³⁻), hydrogen phosphate ion (HPO₄²⁻), dihydrogen phosphate ion (H₂PO⁴⁻) and trihydrogen phosphate(H₃PO₄)). Suitable oxyacids of phosphorus include but are not limited tophosphorous acid (H₃PO₃), phosphoric acid (H₃PO₄), hydrophosphorous acid(H₃PO₂).

The amount of phosphorus contained in the aqueous impregnation solutionis such as to provide a calcined particle having a phosphorus content inthe range of from 0.8 wt. % to 4 wt. % phosphorous, based on the totaldry weight of the calcined particle calculated assuming the phosphorusis in the form of phosphorus pentoxide (P₂O₅). Preferably, theconcentration of phosphorus pentoxide in the calcined particle is in therange of from 1 wt. % to 3.75 wt. %, and, most preferably, theconcentration is in the range of from 1.25 wt. % to 3.5 wt. %.

In an embodiment of the invention, the difference between the amount ofphosphorus in the calcined catalyst particle and the amount of Group 6metal in the calcined catalyst particle is maintained at or above aspecified level. The total quantity of phosphorus in the calcinedparticle (calculated as phosphorus pentoxide) should be more than 5% ofthe total quantity of Group 6 metal present in the calcined catalystparticle (calculated as an oxide) and less than 30%. In a preferredembodiment, molybdenum is the preferred Group 6 metal and the totalquantity of phosphorus in the calcined catalyst particle (calculated asphosphorus pentoxide) is greater than 10% of the total quantity ofmolybdenum in the calcined catalyst particle (calculated as molybdenumtrioxide) and less than 30%.

In preparing the catalyst composition of the invention, the calcinedsupport particle is impregnated with the aforedescribed aqueousimpregnation solution by any of the suitable known impregnation methods,such as, spray impregnation, soaking, multi-dip procedures, andincipient wetness impregnation, to provide the impregnated supportparticle.

The impregnated support particle is then dried to remove a portion ofthe free water or volatiles content from the impregnated supportparticle. The drying temperature is typically in the range of from about75° C. to 250° C. The time period for drying the impregnated supportparticles is any suitable period of time necessary to provide for thedesired amount of reduction in the volatile content of the particlesprior to the controlled low-temperature calcination of the impregnatedsupport particle.

A critical feature of the invention is for the impregnated supportparticle to undergo a controlled, low-temperature calcination to providethe final calcined particle of the inventive catalyst composition. Asnoted above, a feature of the invention involves the high-temperaturecalcination of the support particle in combination with thelow-temperature calcination of the impregnated calcined support particleto provide the final catalyst composition having enhanced catalyticproperties. What is meant herein by low-temperature calcination is thatthe temperature under which the impregnated support particle is calcinedis comparatively lower than the temperature under which the formedsupport particle of the catalyst composition is calcined.

It is important for the low-temperature calcination to be controlled sothat the calcination temperature is maintained at the lower temperaturesrequired in order to minimize the amount of nickel of the impregnatedsupport particle that moves into the lattice structure of the alumina ofthe impregnated support particle or that reacts with the alumina of theimpregnated support particle to form nickel aluminate. The binding ofthe nickel atoms with the alumina is an undesired result of calcinationat higher temperatures, and, thus, the calcination temperature needs tobe controlled in a manner so as to minimize this effect.

The calcination temperature may be adjusted or controlled or set so asto provide a final calcined catalyst particle that has a certainspecified nickel metal acid extractability property (as defined below).The nickel metal acid extractability property of the calcined catalystparticle is an indicator of how tightly the nickel content is bound tothe alumina as opposed to sitting upon the surfaces of the molybdenum ormolybdenum stacks contained within the calcined catalyst particle. Alower percentage of nickel that is extracted from the calcined catalystparticle is indicative of a high percentage of nickel that is tightly orstrongly bound to the catalyst matrix potentially in the form of nickelaluminate. A high percentage of nickel that is extracted from thecalcined catalyst particle, on the other hand, is indicative of a highpercentage of nickel that is loosely held within the structure of thecalcined catalyst particle, thus, suggesting that the loosely heldnickel is residing upon the surfaces of the molybdenum or molybdenumstacks.

The low-temperature calcination of the impregnated support particle ispreferably controlled so as to provide a calcined catalyst particlehaving a desired percentage nickel metal acid extractability property,as hereinafter expressed. This calcination step is conducted in thepresence of an oxygen-containing fluid, such as air, at a temperaturethat is lower than the temperature at which the formed support particleis calcined that yields the calcined support particle, typically, at alow-temperature calcination temperature that is less than 450° C. (842°F.).

More specifically, the temperature at which the low-temperaturecalcination of the impregnated support is conducted is in the range offrom 300° C. (572° F.) to or less than 450° C. (842° F.). A preferredlow-temperature calcination temperature is in the range of from 325° C.(617° F.) to 440° C. (824° F.), more preferred, such temperature is inthe range of from 350° C. (662° F.) to 435° C. (815° F.). Mostpreferred, the low-temperature calcination temperature is in the rangeof from 400° C. (752° F.) to 435° C. (815° F.).

The low-temperature calcination is conducted for a time period necessaryto provide for the desired amount of calcination and a calcined catalystparticle having the properties described herein. Typically, thelow-temperature calcinations is conducted for a period of time in therange of from 0.1 hours to 24 hours. A more typical time period,however, is from 0.5 hours to 12 hours.

The calcined catalyst particle should have a nickel metal acidextractability property that is at least 50%. The methodology formeasuring or determining the nickel metal acid extractability of a givencatalyst is described in detail in Example 3 below. The temperature atwhich the low-temperature calcination of the impregnated supportparticle is conducted is preferably controlled so as to provide thedesired nickel metal acid extractability property, which is at least50%. However, a preferred nickel metal acid extractability property forthe calcined catalyst particle is at least or greater than 55%, and,more preferred, it is greater than 60%. It is most preferred for thenickel metal acid extractability property to be greater than 65%. Theremay be a practical upper limit for the nickel metal acid extractabilityproperty, but it is not known. It possibly can be a nickel metal acidextractability property of less than 98% or even less than 90%.

In addition to the nickel metal acid extractability property of thecalcined catalyst particle, the calcined catalyst particle can furtherbe characterized by certain of its pore structure properties such astotal pore volume, mean pore diameter, and surface area. The total porevolume of the calcined catalyst particle typically exceeds 0.5 cc/g andmay be in the range of from 0.5 cc/g to 1 cc/g. The percentage of thetotal pore volume that is contained in the pores having a diameter inthe range of from 70 Å to 150 Å is in the range of from 50% to 98%. Itis preferred that from 60% to 97% of the total pore volume of thecalcined particle to be contained in its pores having a diameter in therange of from 70 Å to 150 Å. It is more preferred for from 70% to 95% ofthe total pore volume of the calcined particle to be contained in itspores having a diameter in the range of from 70 Å to 150 Å. The meanpore diameter of the calcined catalyst typically can be in the range ofform 80 Å to 130 Å.

The calcined catalyst particles can have a surface area (determined bythe BET method employing N₂, ASTM test method D 3037) that is in therange of from 75 m²/g to 450 m²/g preferably from100 m²/g to 400 m²/g,and, most preferably, from 150 m²/g to 350 m²/g.

The catalyst composition of the invention may be employed as a part ofany suitable reactor system that provides for contacting it or aderivative thereof with a hydrocarbon feedstock under suitablehydroprocessing conditions that may include the presence of hydrogen andan elevated total pressure and temperature. Such suitable reactionsystems can include fixed catalyst bed systems, ebullating catalyst bedsystems, slurried catalyst systems, and fluidized catalyst bed systems.The preferred reactor system is that which includes a fixed bed of theinventive catalyst contained within a reactor vessel equipped with areactor feed inlet means, such as a feed nozzle, for introducing thehydrocarbon feedstock into the reactor vessel, and a reactor effluentoutlet means, such as an effluent outlet nozzle, for withdrawing thereactor effluent or the treated hydrocarbon product from the reactorvessel.

The hydroprocessing process generally operates at a hydroprocessingreaction pressure in the range of from 689.5 kPa (100 psig) to 13,789kPa (3000 psig), preferably from 1896 kPa (275 psig) to 10,342 kPa(22500 psig), and, more preferably, from 2068.5 kPa (300 psig) to 8619kPa (2350 psig).

The hydroprocessing reaction temperature is generally in the range offrom 200° C. to 450° C., preferably, from 260° C. to 415° C., and, mostpreferably, from 320° C. to 410° C.

The flow rate at which the hydrocarbon feedstock is charged to thereaction zone of the inventive process is generally such as to provide aliquid hourly space velocity (LHSV) in the range of from 0.01 hr⁻¹ to 10hr⁻¹. The term “liquid hourly space velocity”, as used herein, means thenumerical ratio of the rate at which the hydrocarbon feedstock ischarged to the reaction zone of the inventive process in volume per hourdivided by the volume of catalyst contained in the reaction zone towhich the hydrocarbon feedstock is charged. The preferred LHSV is in therange of from 0.05 hr⁻¹ to 5 hr⁻¹, more preferably, from 0.1 hr⁻¹ to 3hr⁻¹ and, most preferably, from 0.15 hr⁻¹ to 2 hr⁻¹.

It is preferred to charge hydrogen along with the hydrocarbon feedstockto the reaction zone of the inventive process. In this instance, thehydrogen is sometimes referred to as hydrogen treat gas. The hydrogentreat gas rate is the amount of hydrogen relative to the amount ofhydrocarbon feedstock charged to the reaction zone and generally is inthe range upwardly to 1781 m³/m³ (10,000 SCF/bbl). It is preferred forthe treat gas rate to be in the range of from 89 m³/m³ (500 SCF/bbl) to1781 m³/m³ (10,000 SCF/bbl), more preferably, from 178 m³/m³ (1,000SCF/bbl) to 1602 m³/m³ (9,000 SCF/bbl), and, most preferably, from 356m³/m³ (2,000 SCF/bbl) to 1425 m³/m³ (8,000 SCF/bbl).

The following examples are presented to illustrate certain aspects ofthe invention, but they are not to be construed as limiting the scope ofthe invention.

EXAMPLE 1

This Example 1 describes the preparation and composition of oneexemplary catalyst composition according to the invention.

Table 1 shows the components used in preparing the inventive catalyst ofthis Example 1 that include a molybdenum component, a nickel component,a phosphorus component, and an alumina component.

TABLE 1 Source % metal wt. % metal oxide MoO₃ 9.5 Mo 14.25 NiO 3.5 Ni 4.41 H₃PO₄ (85%-Aldrich) 1.5 P  3.37 as (P₂O₅) alumina n/a 77.97

The alumina support particle was made by mixing (mulling) alumina(Al₂O₃) with 1 wt % Ni as nickel nitrate (wt % based on total weight ofalumina and nickel nitrate), nitric acid and water so as to provide anextrudable mixture or paste. This extrudable mixture was extruded toform tri-lobed support particles. The support particles were then driedat 107° C. followed by calcining for one hour at 649° C. (1200° F.) toprovide calcined support particles. The calcined support particles,comprising alumina as the inorganic oxide material, had thecharacteristics shown in Table 2.

TABLE 2 Properties of the Alumina Support of Table 1 Surface Area (N₂),m²/g 287 Median Pore Diameter Å 98 Total Hg Pore Volume, cc/g 0.827

The aqueous impregnation solution used to incorporate the metalcomponents of the catalyst composition into the calcined supportparticles was prepared by combining NiO, MoO₃ and H₃PO₄ with deionizedwater and heating the components at 93° C. while stiffing until thesolution was clear (about 2 hours). The nickel-to-molybdenum atomicratio of the aqueous impregnation solution was in the range of from 0.4to 0.75. The aqueous impregnation solution was allowed to cool beforeits use and had a pH of 2.19.

Following cooling of the aqueous impregnation solution, it was combinedwith the calcined support particles. The aqueous impregnation solutionand calcined support particles were allowed to age for 2 hours withoccasional shaking. The impregnated support particles were then driedfor four hours at 100° C. resulting in dried impregnated supportparticles having a bulk density of 0.75 g/ml. The loss on ignition wasmeasured at 6.60%.

The dried impregnated support particles were then calcined at 427° C.(800° F.) for two hours resulting in a calcined particle having a N₂surface area of 204 m²/g and a compacted bulk density of 0.67 g/ml. Thetotal pore volume was 0.583 cc/g. The median pore diameter was 111 Å.The Hg pore size distribution measured by mercury penetration accordingto ASTM D-4284 for the calcined catalyst particles is shown in Table 3.

TABLE 3 Hg Pore Size Distribution as Percentage of Total Range in Å % oftotal  <70 1.84  70-100 24.93 100-130 64.08 130-150 5.06 150-180 1.07150-200 0.37 200-240 0.46 240-300 0.40 300-350 0.16 350-450 0.29 450-6000.28  600-1000 0.26 1000-3000 0.32 3000-5000 0.07 >5000 0.40

EXAMPLE 2

This Example 2 describes the preparation and composition of a secondexemplary catalyst composition according to the invention.

Table 4 shows the components used in preparing the inventive catalyst ofthis Example 2 that include a molybdenum component, a nickel component,a phosphorus component, and an alumina component. The support particleutilized in this Example 2 was the same as in Example 1.

TABLE 4 Source % metal wt. % metal oxide MoO₃ 9.5 Mo 14.3 NiO 3.5 Ni 4.45 H₃PO₄ 1.5 P  3.4 as (P₂O₅) alumina 77.8 77.8

The aqueous impregnation solution used to incorporate the metalcomponents of the catalyst composition into the calcined supportparticles was prepared by combining NiO, MoO₃ and H₃PO₄ with deionizedwater and heating the components at 93° C. while stiffing until thesolution was clear (about 2 hours). The nickel-to-molybdenum atomicratio of the aqueous impregnation solution was in the range of from 0.5to 0.75.

Following cooling of the aqueous impregnation solution, it was combinedwith the calcined support particles. The aqueous impregnation solutionand calcined support particles were allowed to age for 2 hours withoccasional shaking.

The impregnated support particles were then divided into two portionswith the first portion being dried for 1 hour at 121° C., and the secondportion being dried for four hours at 100° C. Both portions werecalcined for two hours at 427° C. resulting in calcined particles havinga compacted bulk density of 0.672 g/cc for the sample dried at 121° C.and 0.678 g/cc for the sample dried at 100° C.

The Hg pore size distribution for the calcined particles is shown inTable 5.

TABLE 5 Hg Pore Size Distribution as Percentage of Total Range in Å % oftotal (121° C.) % of total (100° C.)  <70 1.82 1.84  70-100 27.50 26.92100-130 61.95 62.25 130-150 4.09 4.53 150-180 1.24 1.20 150-200 0.460.43 200-240 0.51 0.54 240-300 0.41 0.43 300-350 0.23 0.23 350-450 0.300.29 450-600 .031 0.28  600-1000 0.29 0.27 1000-3000 0.42 0.36 3000-50000.11 0.10 >5000 0.36 .031

EXAMPLE 3

This example describes an acid extraction procedure that may be used todetermine the nickel metal acid extractability property of the inventiveimpregnated support particle that has been subjected to a controlledlow-temperature calcination to provide the calcined catalyst particle inaccordance with the invention.

Generally speaking, the acid extraction procedure is conducted bysubjecting a nickel-containing catalyst sample, such as the calcinedcatalyst particle of the invention, to an acid extraction using a diluteaqueous hydrochloric acid solution and determining the percent nickelthat is extracted therefrom. The percent nickel that is extracted fromthe nickel-containing catalyst sample by this procedure is reported asthe acid extractability property of the nickel-containing catalyst. Asdiscussed elsewhere herein, a higher value for the nickel metal acidextractability property is indicative of a higher percentage of looselybound nickel in the alumina matrix of the calcined catalyst particlethan in a calcined catalyst particle having a lower value for its nickelmetal acid extractability property; and, thus, indicating a more activecatalyst.

More specifically, the acid extraction procedure is conducted bydetermining the amount of nickel that is contained in a sample ofnickel-containing catalyst and placing a measured weight (e.g., grams)of the nickel-containing catalyst sample into a container. A measuredamount (e.g., milliliters) of dilute aqueous hydrochloric acid solutionhaving a concentration of 0.98% is then placed into the container withthe measured amount of the nickel-containing catalyst sample. The ratioof weight of nickel-containing catalyst sample in grams to the volume ofdilute aqueous hydrochloric acid solution in milliliters is 0.5 gm/ml.

The container is sealed, and the contents are rotated for one hour whilemaintaining the contents at a temperature between about 17 to 30° C.After the rotation is complete, the aqueous hydrochloric acid solutionis then separated from the nickel-containing catalyst sample particlesby filtration and analyzed using any suitable method for measuring thenickel content of the solution, such as, for example, by x-rayfluorescence (XRF), to determine the amount of nickel extracted from thecatalyst sample. The nickel metal acid extractability property of thecatalyst sample is calculated and reported as the weight percent ofnickel contained in the original sample of impregnated and calcinedcatalyst particles that is extracted therefrom by the dilute aqueoushydrochloric acid solution.

The specific acid extraction procedure used herein to measure the nickelmetal extractability property of the catalyst composition of theinvention is described as follows.

-   1. A sample amount of catalyst particles is dried in an oven set at    300±10° C. for one hour±10 minutes. The catalyst particles of the    sample are not ground.-   2. The sample of dried catalyst particles is placed in a dessicator    and allowed to cool for at least approximately 20 minutes.-   3. Å stock dilute HCl acid solution, prepared by combining 10 volume    units of concentrated HCl (36.5-38%) with 390 volume units of    deionized (DI) water, is used in the acid extraction procedure for    determining the nickel metal acid extractability property of the    sample of catalyst particles.-   4. 10.0±0.5 grams of the pre-dried sample catalyst particles and    20±0.5 ml of the stock dilute HCl acid solution are placed into a    125 ml bottle container that is then capped and placed on a roller    assembly that is rotated for one hour±5 minutes at a rate of    approximately 60 rpm.-   5. When the rolling is complete, the extraction liquid is separated    from the catalyst particles and analyzed for its nickel content,    which value is used to calculate the percentage nickel metal    contained in the original catalyst particles that is extracted by    the stock dilute HCl acid solution and to provide the nickel metal    acid extractability property for the sample of catalyst particles.-   6. The nickel metal acid extractability property is reported as    weight percent (%) of the total nickel content of the original    catalyst particles, before the acid extraction treatment, that is    extracted with the stock dilute HCl acid solution in the acid    extraction treatment procedure.

Samples of the calcined particles produced in accordance with Examples 1and 2 were tested to determine their nickel metal acid extractabilityproperty. The nickel metal acid extractability property of the calcinedparticles of Example 1 was measured to be 62%. The nickel metal acidextractability property of the calcined particles of Example 2 that weredried at 121° C. was measured to be 61% and that of the calcinedparticles of Example 2 that were dried at showed at 100° C. was measuredto be 63%.

EXAMPLE 5

This Example 5 generally describes the testing procedure used todetermine various of the performance properties of the inventivecatalyst compositions described in Examples 1 and 2, and a comparisoncatalyst composition, and it presents summary information by use of theplots presented in FIGS. 1-4.

FIGS. 1-4 illustrate the improved hydrodesulfurization,hydrodenitrogenation and MCR conversion capabilities of the inventivecatalyst relative to such properties of a comparison catalyst when usedin a simulated commercial reactor testing apparatus to treat a typicalheavy hydrocarbon feedstock.

The comparison catalyst was a commercially available resid hydrotreatingcatalyst prepared using an impregnation technique to incorporate theactive nickel and molybdenum metal components into an alumina support.The alumina support did not contain a nickel component when the activemetals were incorporated onto it. The comparison catalyst contained 8.2weight percent molybdenum, reported as metal and not as an oxide, 2.3weight percent nickel, reported as metal and not as an oxide, and nophosphorous. The nickel metal acid extractability property of thecomparison catalyst was less than 30%.

The feed was a heavy feedstock characterized as follows: T10=582° F.;T90=1283° F.; End Point=1351° F.; sulfur content=1.1 wt. %; nitrogencontent=1760 ppm.

The reaction conditions were as follows: reaction pressure=1900 psig;H₂/Oil=4000 SCF/bbl; and weight hourly space velocity (WHSV)=0.5 hr⁻¹.

In the FIGS, the black circles represent the reference catalyst datapoints and the open circles represent the inventive catalyst datapoints.

FIG. 1 illustrates that the catalyst composition according to theinvention provides for a significant improvement in sulfur conversion ascompared to the reference catalyst. It may also be seen from FIG. 1that, while the degree of sulfur conversion for the inventive catalystdeclines over time, this rate of decline in sulfur conversion isslightly lower than the rate of decline exhibited by the referencecatalyst.

FIG. 2 illustrates that the catalyst composition according to theinvention provides for significantly lower weight average bedtemperatures (WABT) for a given desulfurization level than does thecomparison catalyst. A lower WABT is advantageous; because, it providesfor significant energy savings in the hydroprocessing of a heavyhydrocarbon feedstock.

FIGS. 3 and 4 show that the inventive catalyst composition also providesfor improved conversion rates for both nitrogen and micro-carbon residue(MCR), respectively, as compared to the comparison catalyst.

It is understood that while particular embodiments of the invention havebeen described herein, reasonable variations, modifications andadaptations thereof may be made that are within the scope of thedescribed disclosure and the appended claims without departing from thescope of the invention as defined by the claims.

That which is claimed is:
 1. A method of making a catalyst compositionuseful in the hydrotreatment of a heavy hydrocarbon feedstock, whereinsaid method comprises the steps of: providing a calcined supportparticle, comprising an inorganic oxide material; impregnating saidcalcined support particle with an aqueous impregnation solution, whereinsaid aqueous impregnation solution comprises a Group 6 metal compound, anickel compound and a phosphorus compound, and wherein said aqueousimpregnation solution has an atomic ratio of nickel metal to a Group 6metal in the range of from 0.5 and 0.75, to thereby provide animpregnated support particle; and conducting a controlledlow-temperature calcination of said impregnated support particle so asto thereby provide a calcined catalyst particle having a nickel metalacid extractability property of at least 40%.
 2. A method according toclaim 1, wherein said calcined catalyst particle contains: a Group 6metal component in an amount in the range of from 8 wt % to 18 wt %; anickel component in an amount in the range of from 2 wt % to 7 wt %; anda phosphorus component in an amount in the range of from 0.8 wt % to 4wt %, all of which are based on the weight of calcined catalyst particleand the metal components as oxides regardless of their actual form.
 3. Amethod according to claim 2, wherein said Group 6 metal component ismolybdenum.
 4. A method according to claim 3, wherein the total quantityof phosphorus in said calcined catalyst particle, calculated asphosphorus pentoxide, is greater than 10% of the total quantity of saidGroup 6 metal component in said calcined catalyst particle, calculatedas molybdenum trioxide.
 5. A method according to claim 4, wherein saidcalcined catalyst particle has a surface area that exceeds 150 m²/g. 6.A method according to claim 5, wherein said calcined catalyst particlehas a mean pore diameter in the range of from 90 Å to 120 Å.
 7. A methodaccording to claim 6, wherein said calcining step comprises calciningsaid particle between 370° C. (698° F.) and 482° C. (900° F.).
 8. Acatalyst composition, comprising: an impregnated calcined supportparticle, having been subjected to a controlled low-temperaturecalcination to provide a calcined particle, wherein said calcinedparticle comprises a Group 6 metal component and a nickel component inproportions such that the atomic ratio of the nickel metal to the Group6 metal is in the range of from 0.5 and 0.75, and wherein said calcinedparticle has a nickel metal acid extractability property of at least50%.
 9. A catalyst composition according to claim 8, wherein saidcalcined particle contains: a Group 6 metal component in an amount inthe range of from 8 wt % to 18 wt %; a nickel component in an amount inthe range of from 2 wt % to 7 wt %; and a phosphorus component in anamount in the range of from 0.8 wt % to 4 wt %, all of which are basedon the weight of calcined particle and the metal components as oxidesregardless of their actual form.
 10. A catalyst composition according toclaim 9, wherein said Group 6 metal component is molybdenum.
 11. Acatalyst composition according to claim 10, wherein the total quantityof phosphorus in said calcined catalyst particle, calculated asphosphorus pentoxide, is greater than 10% of the total quantity of saidGroup 6 metal component in said calcined catalyst particle, calculatedas molybdenum trioxide.
 12. A catalyst composition according to claim11, wherein said calcined catalyst particle has a surface area thatexceeds 150 m²/g.
 13. A catalyst composition according to claim 5,wherein said calcined catalyst particle has a mean pore diameter in therange of from 80 Å to 100 Å.
 14. A catalyst composition according toclaim 6, wherein said calcining step comprises calcining said particlebetween 370° C. (698° F.) and 538° C. (1000° F.).
 15. A hydrotreatingprocess, comprising: contacting a catalyst composition with ahydrocarbon feedstock under hydrotreating process conditions andyielding a hydrotreated hydrocarbon product, wherein said catalystcomposition comprises an impregnated calcined support particle, havingbeen subjected to a controlled low-temperature calcination to provide acalcined particle, wherein said calcined particle comprises a Group 6metal component and a nickel component in proportions such that theatomic ratio of the nickel metal to the Group 6 metal is in the range offrom 0.5 and 0.75, and wherein said calcined particle has a nickel metalacid extractability property of at least 50%.
 16. A composition preparedby the method of claim
 1. 17. A hydrotreating process, comprisingcontacting the catalyst composition of claim
 8. 18. A hydrotreatingprocess, comprising contacting the composition prepared by the method ofclaim 1 with a hydrocarbon feedstock under hydrotreating processconditions and yielding a hydrotreated hydrocarbon product.